Control of radiotherapy equipment

Abstract

A radiotherapy apparatus, a computer-implemented method, and a computer-readable medium are disclosed. The radiotherapy apparatus includes a radiation source, one or more imaging systems, and a controller communicatively coupled to the radiation source and the one or more imaging systems. The radiation source is configured to apply radiation to a treatment area overlapping with a subject according to a treatment plan. The one or more imaging systems are configured to generate image data for the subject. The controller is configured to: determine the relative distance between a target area of ​​the subject and an organ at risk of the subject based on the image data, wherein the treatment plan includes a prescribed dose for the target area; determine a buffer zone around the target based at least partially on the relative distance; and generate control signals for adjusting the radiotherapy in response to determining, based on the image data, that the treatment area is at least partially outside the buffer zone.

Description

TECHNICAL FIELD

[0001] The present invention relates to generating control signals configured to control operation of a radiotherapy device, and in particular, to generating control signals configured to control operation of a radiotherapy device based on a position of an organ at risk. BACKGROUND

[0002] Radiotherapy can be described as the use of ionizing radiation, such as X-rays, to treat a human or animal body. Radiotherapy is often used to treat a tumor within a patient or subject. In such treatment, ionizing radiation is used to irradiate and destroy or damage cells forming part of the tumor.

[0003] A radiotherapy device typically includes a gantry that supports a beam generating system or other radiation source that can be rotated about a patient. For example, for a linac device, the beam generating system can include a radio frequency energy source, an electron source, an acceleration waveguide, a beam shaping device, etc.

[0004] In radiotherapy, it is desirable to deliver a prescribed dose of radiation to a target region of a subject and limit irradiation of other parts of the subject, i.e., to healthy tissue. Motion of the subject can result in a decrease in the dose applied to the target region and / or an increase in the dose applied to healthy tissue. There are various physiological motions that can contribute to the overall motion of the subject. Gross or large scale movements of the subject can include shifting, coughing, or sneezing. The subject can also make periodic physiological movements. For example, the subject can make respiratory movements due to their breathing cycle and can make cardiac movements based on the beating of their heart. To address this motion, known techniques include monitoring the position and / or movement of the subject and gating the treatment beam so that radiation is applied only when the subject, i.e., the target region within the subject, is in a desired position and not when the subject / target region is in a suboptimal position. In other words, radiation can be applied or not applied (i.e., the beam is gated) based on sensed movement or position of the subject. Other known techniques for addressing movement of the subject include training the patient’s breathing or requiring the patient to hold their breath during radiotherapy.

[0005] In existing methods using x-ray imaging modalities, typically only the bone anatomy of the subject can be seen. Using these methods, the location of a target region or organ within the subject can not be determined during treatment. As a result, the application or gating of radiation therapy can not be as accurate as desired. Some existing methods have used magnetic resonance (MR) imaging integrated with the application of radiation therapy to determine whether the target region is in the desired location. One such method can be performed using Clarity VOICE software. The MR imaging information can be used to inform the gating in order to provide more accurate gating. Radiation is applied only when the target region is in a particular location or within a certain tolerance of that particular location, as determined using MR imaging.

[0006] Currently, gating of a radiation therapy beam is driven based on a constant margin around the target. The constant margin can have a constant predetermined width around the target, or can have a constant width around the target that is set to the maximum absolute distance that the centroid of the target can move without coinciding with a particular structure. During radiation therapy, the subject can move such that the target moves a corresponding or similar distance. If as a result of this, radiation is applied to a location outside of the constant margin around the target, i.e., if it is determined that there is an overlap between a region where radiation is applied and a region where radiation should not be applied, the beam can be gated such that radiation is no longer applied. This helps to ensure adequate irradiation of the target and prevent substantial irradiation of healthy tissue. As part of a method that is conservative, cautious, or risk-averse, the defined constant margin can typically have a uniform, relatively narrow width. This is particularly the case if there is significant uncertainty in the location or movement of the subject or a portion of the subject based on the technology used to monitor the subject.

[0007] However, there are various possible locations of the target (tumor) within the subject's body, and the anatomy surrounding the target will vary greatly depending on its location within the body. Also, the surrounding environment of the target is typically different in different (three-dimensional) directions. While it is desirable to avoid irradiation of any healthy tissue, the risks associated with irradiating certain healthy tissue (e.g., an organ at risk) can be more severe than the risks associated with other healthy tissue. By not taking into account this variation in risk, existing methods can apply a method that is inappropriately cautious for the application of radiation therapy, which can result in suboptimal radiation therapy. Setting an inappropriate wide margin will result in unsafe irradiation of an organ at risk, while setting an inappropriate narrow margin will result in unnecessary gating of the therapy beam. Some healthy tissue can tolerate low or moderate doses of radiation, such that in some scenarios gating of the radiation therapy beam will result in unnecessarily delayed or inefficient radiation therapy.

[0008] It would be advantageous to provide improved means of taking into account and reacting to patient motion during radiotherapy. Also, it would be advantageous to provide improved considerations of the anatomical environment of the target when controlling the treatment beam. Hence, it would be advantageous to provide more accurate control of the treatment beam. In addition, it would be advantageous to provide more effective radiotherapy and higher patient throughput.

[0009] The present invention seeks to address these and other drawbacks encountered in the prior art. SUMMARY

[0010] The invention is set out in the independent claims.

[0011] According to an aspect, there is provided a radiotherapy device comprising: a radiation source configured to apply radiation to a treatment region coinciding with a subject in accordance with a treatment plan; one or more imaging systems configured to generate image data for the subject; and a controller communicatively coupled to the radiation source and the one or more imaging systems, the controller configured to: determine a relative distance between a target region of the subject and an organ at risk of the subject based on the image data, wherein the treatment plan comprises a prescribed dose for the target region; determine a buffer region around the target region based at least in part on the relative distance; and generate a control signal for adjusting the radiotherapy in response to determining that the treatment region coinciding with the subject is at least partially outside the buffer region based on the image data.

[0012] According to another aspect, there is provided a computer-implemented method comprising: receiving image data for a subject from one or more imaging systems; determining a relative distance between a target region of the subject and an organ at risk of the subject based on the image data, wherein the treatment plan comprises a prescribed dose for the target region; determining a buffer region around the target region based at least in part on the relative distance; and generating a control signal for adjusting the radiotherapy in response to the treatment region coinciding with the subject being at least partially outside the buffer region.

[0013] According to another aspect, there is provided a computer-readable medium comprising computer-executable instructions that, when executed by a processor, cause the processor to perform the above method. BRIEF DESCRIPTION OF DRAWINGS

[0014] Specific embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

[0015] Figure 1 A radiotherapy device or apparatus according to the present invention is described;

[0016] Figure 2 A schematic view of a defined region according to the present invention is described;

[0017] Figure 3a And Figure 3bA schematic of a defined zone according to the present application is described;

[0018] Figure 4 A method of controlling a radiotherapy device according to the present application is described;

[0019] Figure 5 A method of generating a control signal for controlling a radiotherapy device according to the present application is described; and

[0020] Figure 6 A block diagram of a computing device configured to perform one or more methods described herein is described. DETAILED DESCRIPTION

[0021] The present application relates to improved control of radiotherapy device operation. A radiotherapy device can include a radiation source configured to apply radiation to a treatment region of a subject and one or more imaging systems configured to generate image data for the subject. A controller communicatively coupled to the radiation source and the one or more imaging systems can be configured to determine a relative distance between a target region (i.e., including a tumor) and an organ at risk (i.e., including healthy tissue that is critical to radiation) based on the image data. The controller can be further configured to determine a buffer region around the target region based at least in part on the relative distance. The buffer region can have different widths in different directions. In particular, the buffer region can have a smaller width in a direction of the organ at risk and a larger width in a different direction that does not correspond to a location of the organ at risk. The controller can be further configured to determine that the treatment region is at least partially outside the buffer region. This determination can be based on the image data generated by the one or more imaging systems. The controller can be configured to generate a control signal for adjusting the radiotherapy in response to determining that the treatment region is at least partially outside the buffer region. The control signal can be configured to adjust an output of the radiation source. For example, the control signal can be configured to gate the radiation source. In this way, a gating algorithm can be driven based on a flexible anisotropic buffer region around the target region and based on the subject’s anatomy. The control signal can be configured to adjust (i.e., reduce) a dose rate applied by the radiation source. In this way, using a flexible anisotropic buffer region and in accordance with the subject’s anatomy, the dose rate can be reduced to a level that is acceptable for the organ at risk. The control signal can be configured to adjust a position and / or orientation of the radiotherapy source, adjust a shape of the radiotherapy beam, and / or adjust a position and / or orientation of a patient positioning surface. This can enable the treatment region to be dynamically realigned with the target region and can prevent regions outside the target region from being irradiated. These techniques can accommodate and mitigate higher risks associated with irradiating the organ at risk while avoiding unnecessarily stopping the radiotherapy.

[0022] Figure 1A radiotherapy device adapted to deliver a radiation beam to a patient during radiotherapy and configured to deliver a radiation beam to a patient is described. To provide useful companion information of the invention, the device and its constituent components will be generally described. Figure 1 The device described in the Summary is in accordance with the invention and is suitable for use with the disclosed systems and apparatuses. While Figure 1 The device in the Summary is an MR linac, but implementations of the invention can be any radiotherapy device, such as a linac device.

[0023] Figure 1 The device 100 described in the Summary is an MR linac. The device 100 includes an MR imaging apparatus 112 and a radiotherapy (RT) apparatus, which can include a linac device. The MR imaging apparatus 112 is shown in cross-section in the figure. In operation, the MR scanner produces MR images of a patient, and the linac device produces and shapes a radiation beam and directs it to a target region in the patient’s body according to a radiotherapy plan. The described device does not have the usual “shell” that would cover the MR imaging apparatus 112 and the RT apparatus in a commercial setting, such as a hospital.

[0024] Figure 1 The MR linac device described in the Summary includes a radio frequency wave source 102, a waveguide 104, an electron source 106, a radiation source, a collimator 108 configured to collimate and shape the beam, such as a multi-leaf collimator, an MR imaging apparatus 112, and a patient support surface 114. In use, the device will also include a shell (not shown) that defines a bore with the ring gantry. The movable support surface 114 can be used to move a patient or other subject into the bore at the start of an MR scan and / or radiotherapy. The MR imaging apparatus 112, the RT apparatus, and the subject support surface actuator are communicatively coupled to a controller or processor. The controller is also communicatively coupled to a storage device including computer executable instructions that can be executed by the controller.

[0025] The RT apparatus includes a radiation source and a radiation detector (not shown). Typically, the radiation detector is positioned diametrically opposite the radiation source. The radiation detector is adapted and configured to produce radiation intensity data. In particular, the radiation detector is positioned and configured to detect the intensity of radiation that passes through the subject. The radiation detector can also be described as a radiation detection apparatus and can form part of a portal imaging system.

[0026] The radiation source can include a beam generation system. For a linac, the beam generation system can include an RF energy source 102, an electron gun 106, and a waveguide 104. The radiation source is attached to a rotatable gantry 116 so as to rotate with the gantry 116. In this way, the radiation source can rotate around the patient so that the treatment beam 110 can be applied from different angles around the gantry 116. In preferred implementations, the gantry is continuously rotatable. In other words, the gantry can rotate 360 degrees around the patient and can in fact continue to rotate beyond 360 degrees. The gantry can be toroidal. In other words, the gantry can be a toroidal gantry.

[0027] A radio frequency wave source 102, such as a magnetron, is configured to generate radio frequency waves. The radio frequency wave source 102 is coupled to the waveguide 104 via a circulator 118 and is configured to pulse radio frequency waves into the waveguide 104. The radio frequency waves can pass from the radio frequency wave source 102 through an RF input window and into an RF input connection tube or pipe. An electron source 106, such as an electron gun, is also coupled to the waveguide 104 and is configured to inject electrons into the waveguide 104. In the electron gun 106, electrons are thermionically emitted from a cathode filament when the filament is heated. The temperature of the filament controls the number of electrons injected. The electrons are injected into the waveguide 104 in synchronization with the pumping of the radio frequency waves into the waveguide 104. The design and operation of the radio frequency wave source 102, the electron source, and the waveguide 104 is such that the radio frequency waves accelerate the electrons to very high energies as the electrons propagate through the waveguide 104.

[0028] The design of the waveguide 104 depends on whether the linac is using standing waves or traveling waves to accelerate the electrons, but the waveguide generally includes a series of cells or cavities, each connected by a hole or “iris” through which the electron beam can pass. The cavities are coupled so as to produce the appropriate electric field pattern that accelerates the electrons propagating through the waveguide 104. The electron beam path is controlled by an appropriate arrangement of steering magnets or steering coils around the waveguide 104 as the electrons are accelerated in the waveguide 104. The arrangement of steering magnets can include, for example, two sets of quadrupole magnets.

[0029] Once the electrons are accelerated, they can enter a flight tube. The flight tube can be connected to the waveguide by a connection tube. This connection tube or connection structure can be referred to as a drift tube. The electrons travel toward a heavy metal target, which can include, for example, tungsten. An arrangement of focusing magnets is used to direct and focus the beam on the target as the electrons travel through the flight tube.

[0030] To ensure that the propagation of the electrons is not impeded as the electron beam travels toward the target, a vacuum system, including an arrangement of vacuum pumps or vacuum pumps, evacuates the waveguide 104. The pump system is capable of producing ultra-high vacuum (UHV) conditions in the waveguide 104 and the flight tube. The vacuum system also ensures UHV conditions in the electron gun. The electrons can be accelerated to speeds close to the speed of light in the evacuated waveguide 104.

[0031] A radiation source is configured to direct a therapeutic radiation beam 110 toward a patient positioned on a patient support surface 114. The radiation source may include a heavy metal target, to which high-energy electrons exiting a waveguide are directed. When the electrons strike the target, X-rays are generated in various directions. A master collimator may block X-rays traveling in certain directions and allow only forward-traveling X-rays to pass through to generate the therapeutic beam 110. The X-rays may be filtered and may pass through one or more ionization chambers for dose measurement. Before the beam enters the patient as part of radiotherapy, it may be shaped in various ways by a beamforming device, such as by using a multi-leaf collimator 108.

[0032] In some implementations, the radiation source is configured to emit either an X-ray beam or an electron particle beam. This allows the device to provide electron beam therapy, i.e., an external beam therapy that directs electrons, rather than X-rays, to the target area. By adjusting components of the linear accelerator, a first mode emitting X-rays can be “swapped” from a second mode emitting electrons. Essentially, this switching is achieved by moving the heavy metal target into or out of the electron beam path and replacing it with a so-called “electron window.” The electron window is substantially transparent to the electrons and allows them to exit the flight tube.

[0033] A subject or patient support surface is configured to move between a first position generally outside the aperture and a second position generally inside the aperture. In the first position, the patient or subject can mount the patient support surface. The support surface 114 and the patient can then move inside the aperture to the second position to image the patient via MR imaging device 112 and / or to image or treat the patient using RT device. The movement of the patient support surface is achieved and controlled by a subject support surface actuator, which can be described as an actuation mechanism. The actuation mechanism is configured to move the subject support surface in a direction parallel to and defined by the central axis of the aperture. The terms “subject” and “patient” are used interchangeably herein, such that the subject support surface can also be described as a patient support surface. The subject support surface can also be referred to as a movable or adjustable examination table or worktable.

[0034] Figure 1 The radiotherapy apparatus / device described herein also includes an MR imaging device 112. The MR imaging device 112 is configured to acquire images of a subject positioned (i.e., located on) a subject support surface. The MR imaging device 112 may also be referred to as an MR imager. The MR imaging device 112 may be a conventional MR imaging device that operates in a known manner to acquire MR data (e.g., MR images). Those skilled in the art will understand that such an MR imaging device 112 may include a main magnet, one or more gradient coils, one or more receiving coils, and an RF pulse applicator. The operation of the MR imaging device is controlled by a controller.

[0035] The controller is a computer, processor, or other processing device. The controller may be formed from several discrete processors; for example, the controller may include: an MR imaging device processor that controls the MR imaging device 110; an RT device processor that controls the operation of the RT device; and a subject support surface processor that controls the operation and actuation of the subject support surface. The controller is communicatively coupled to a memory (e.g., a computer-readable medium).

[0036] Linear accelerator equipment also includes several other components and systems as those skilled in the art will understand. For example, appropriate shielding is provided to ensure that the linear accelerator does not leak radiation.

[0037] Treatment administration may include, for example, the application of radiation from a radiation source according to a treatment plan. The radiation source may rotate around the subject. This rotation may be continuous or pseudo-continuous, such that the dose is applied from a continuous or pseudo-continuous range of angles. In other examples, the rotation may be to multiple discrete angles, such that the dose is applied from a discrete series of angles. The rotation of the radiation source may be predetermined according to the treatment plan. The treatment plan may include a prescribed dose (e.g., a clinically prescribed dose) for the target area. The prescribed dose may be a function of spatial coordinates, such as in one, two, or three spatial dimensions. For example, the prescribed dose may vary spatially to account for the concentration of unhealthy tissue within the subject.

[0038] Different subjects may have different distributions or concentrations of unhealthy tissue. For example, different subjects may have tumors of different sizes, locations, and / or shapes. Therefore, a specific treatment plan for radiation therapy can be determined for each subject and / or each tumor. Determining a treatment plan may involve acquiring data specific to the subject. For example, MR imaging, computed tomography (CT), ultrasound, and / or other techniques can be used to derive images of structures within the subject's body. Alternatively or additionally, data can be provided based on clinical (e.g., internal) examinations. This can provide information about tumor distribution as well as information about the distribution of healthy tissue (e.g., organs at risk (OARs)).

[0039] When determining a treatment plan, one or more zones or volumes within the subject can be defined. Figure 2Schematic diagrams of some such regions or volumes according to the invention are described. It will be understood that additional and / or alternative volumes may be defined. Total tumor volume (GTV) 200 can be defined as the total, palpable, visible, or clinically verifiable location and extent of malignant growth. Clinical target volume (CTV) 202 can be defined as the volume of tissue containing GTV 200 plus subclinical malignancy that may be at risk and requires treatment. GTV 200 and CTV 202 are therefore anatomical volumes within the subject, relating to the distribution of unhealthy tissue and / or the probability of such distribution. Planning target volume (PTV) 204 can be defined as the volume including CTV 202 (and GTV 200) plus an additional margin that compensates for uncertainties and / or variations related to the accuracy or setup of the radiotherapy beam and / or the location uncertainty of the target area. Thus, PTV 204 is the geometric volume used to select the beam arrangement for applying a prescribed dose to CTV 202. When determining the aforementioned volume and treatment plan, simulations of instances of radiotherapy can be used to provide a treatment beam geometry suitable for the specific target area of ​​the subject.

[0040] like Figure 2 The GTV 200, CTV 202, and PTV 204 may correspond to the relative extents of these respective volumes in a specific plane, such as a specific depth and orientation within the patient. At other depths and / or other orientations, the representation of these respective volume extents may differ. Figure 2 Those mentioned above. For example... Figure 2 The GTV 200, CTV 202, and PTV 204 described provide specific examples of the distribution of unhealthy tissue (e.g., tumors). It will be understood that various other subject-specific distributions may also occur, and any such other distributions are considered to be within the scope of this invention.

[0041] In some examples, CTV 202 may extend beyond GTV 200 by different distances in different directions. In some examples, the range of CTV 202 may coincide with the range of GTV 200 at one or more points or in one or more directions. In some examples, the range of CTV 202 may differ from the range of GTV 200 by a constant distance. In some examples, PTV 204 may extend beyond GTV and / or CTV 202 by different distances in different directions. In some examples, the range of PTV 204 may coincide with the range of GTV 200 and / or CTV 202 at one or more points or in one or more directions. In some examples, the range of PTV 204 may differ from the range of GTV 200 and / or CTV 202 by a constant distance.

[0042] Based on the above considerations, and as part of determining the treatment plan, it can be determined that a specific dose of radiation should be applied to a specific target area or target volume of the subject. The terms target volume, target area, and PTV 204 are used interchangeably herein. A target area can be a two-dimensional region (i.e., area) or a three-dimensional region (i.e., volume). A constraint can be imposed that the PTV 204 should receive a specified dose of radiation as part of radiotherapy.

[0043] Based on the above considerations, determining a treatment plan may include using dose management / calculation software to indicate the distribution of the expected dose. For example, voxels (i.e., discrete volume elements of the subject) can be associated with the expected dose. Isodose can be defined as an expected dose of equal intensity applied to more than one point. Therefore, an isodose curve can be defined as a line connecting points receiving equal expected doses. Similarly, an isodose surface can be defined as a surface connecting points receiving equal expected doses. In other words, all points on an isodose surface are expected to receive the same dose. As used herein, an isodose surface can be a two-dimensional surface enclosing an area or a three-dimensional surface enclosing a volume. Although the accompanying drawings of the invention depict two-dimensional views for ease of understanding, these can be understood as two-dimensional representations of three-dimensional features, e.g., projected onto a two-dimensional plane.

[0044] Due to considerations related to beam geometry, the expected dose can monotonically increase toward the center point with the maximum expected dose. An isodose plane can enclose a region within which a specific dose (or at least a specific dose) will be received. Treatment planning can be determined using a “top-cap” dose profile such that the expected dose distribution is flatter within the target area than immediately outside the target area, thus providing a relatively constant expected dose at the target area and a relatively sharp decrease in expected dose outside the target area.

[0045] Figure 3a and Figure 3b A schematic diagram of the defined region according to the present invention is described. Figure 3a PTV 204 is described, which can correspond to Figure 2 PTV 204. Figure 3a For ease of understanding, GTV 200 and CTV 202 are not described here, but it will be understood that these can be considered as comparable to... Figure 2 The method shown is similar to that used in PTV 204, where it is nested within the same structure.

[0046] Figure 3aTreatment area 300 is also described. Treatment area 300 includes PTV 204. Due to limitations associated with irradiation techniques, it may be impossible or practically impossible to irradiate the area precisely corresponding to PTV 204 at a prescribed dose. For example, for some tumors, PTV 204 may have a particularly irregular shape, making it difficult to design and implement a beam geometry and dose that irradiates PTV 204 and only PTV 204 at a prescribed dose. Therefore, treatment area 300 may be larger than PTV 204 and may have a simpler shape than PTV 204. It can be determined that PTV 204 should receive at least a prescribed dose of radiation according to clinical requirements. Treatment area 300 is the area that is actually planned to receive at least that prescribed dose of radiation based on the treatment plan. Treatment area 300 may be described as treatment area 300 for the subject or treatment area 300 overlapping with the subject or a portion of the subject.

[0047] Figure 3a The organ at risk, or OAR 302, is also described. Similar to the extension from CTV 202 to PTV 204 to account for uncertainties, OAR 302 can be extended to the planned risk volume (PRV). In other words, the PRV is the volume that includes OAR 302 plus an additional margin that compensates for uncertainties and / or variations related to the accuracy or setup of the radiotherapy beam and / or the location uncertainty of OAR 302. As used herein, the terms OAR 302 and PRV are used interchangeably. OAR 302 can be positioned adjacent to a first side of PTV 204, i.e., it can be located in a first direction starting from PTV 204. OAR 302 can be located at a certain relative distance from PTV 204. As used herein, the relative distance can also be referred to as distance or separation distance. This relative distance describes the distance between OAR 302 and the target area / PTV 204 when one or more of OAR 302 and the target area / PTV 204 may be moving (e.g., moving relative to each other). This relative distance can refer to the distance between OAR 302 and the target area / PTV 204 at a specific point in time. In this illustrative example, on the second side of PTV 204 (i.e., Figure 3a On the left side, in the second direction starting from PTV 204, there may not be an OAR302 located at a similar or smaller distance from PTV 204.

[0048] Figure 3aBuffer 304 is also described. Buffer 304 includes a housing arranged around PTV 204. Buffer 304 can be used in a drive algorithm for controlling the radiotherapy device 100. For example, buffer 304 can be used to determine whether to adjust radiotherapy. Buffer 304 can be determined at least in part based on the relative distance between PTV 204 and OAR 302. On a first side of PTV 204, adjacent to OAR 302, the buffer can have a first width w1. In some examples, and as... Figure 3a As shown, the first width w1 may be equal to the relative distance between PTV 204 and OAR 302. In other examples, the first width w1 may be equal to the relative distance plus or minus a specific absolute distance or a specific percentage of the absolute distance. These include options that can be used to increase or decrease the sensitivity of radiotherapy to changes in the position of PTV 204 and / or OAR 302, and can be determined based on a balance between the safety, efficiency, and / or prognosis of the subject. This determination may be based on which specific organ (heart, brain, etc.) OAR 302 corresponds to and / or the dose rate of the applied radiation.

[0049] Buffer 304 can be anisotropic. Buffer 304 can be asymmetric along any given plane and can extend beyond PTV 204 to varying degrees in different directions. In other words, the width of buffer 304 does not necessarily correspond to w1 around PTV 204. Figure 3b As shown, buffer 304 has a second width w2 along a second direction on the second side of PTV 204. The second width w2 can be greater than the first width w1. Since no OAR is located on the second side of PTV 204, or at least no OAR is positioned as close to the second side of PTV 204 as OAR 302 is positioned as close to the first side of PTV 204, it can be determined that the second width w2 is greater than the first width w1.

[0050] In some examples, the controller may first determine a constant buffer 304 of a first width w1 based on the relative distance between PTV 204 and OAR 302 on a first side of PTV 204, and then may increase the width of buffer 304 on other sides of PTV 204 (e.g., increasing it to a second width w2 in a second direction). The width of buffer 304 may be increased on these other sides until it reaches a different OAR, or until it enters within a predetermined distance of the OAR, or until it reaches a predetermined maximum. In some examples, the controller may first determine a constant buffer 304 of a second width w2 based on the absence of an OAR on a second side of PTV 204, and then may decrease the width of buffer 304 on other sides of PTV 204 (e.g., decreasing it to a first width w1 in a first direction). The width of buffer 304 may be decreased on these other sides to prevent overlap with an OAR, or to prevent overlap with a position within a predetermined distance of the OAR, or until it reaches a predetermined minimum. During treatment, the width of the buffer can be dynamically increased and / or decreased in different directions, for example, to accommodate movement of the subject, PTV 204, and / or organs at risk, such as those identified using image data.

[0051] In some examples, the controller may determine the shape of PTV 204 and / or OAR 302 based on image data. The controller may determine a buffer zone 304 around PTV 204 based at least in part on the shape of PTV 204 and / or OAR 302. The shape of PTV 204 and / or the shape of the organ at risk 302 may alternatively be predefined based on pretreatment imaging or examination. The shape of PTV 204 and / or OAR 302 may be defined and considered in two or three dimensions. These steps of considering the shape of these zones may be performed, in addition to, or as an alternative to, determining the relative distances and the buffer zone 304 based on those relative distances. Consideration of one or more shapes of one or more zones incorporates additional information about PTV 204 and OAR 302 (as opposed to considering only the relative distances between these features). This can provide safer and more accurate control of the radiotherapy device by considering the spatial distribution of these features rather than just their separation distances. This is particularly beneficial when the shape of PTV 204 is particularly irregular (e.g., due to the tumor having a particularly irregular shape) and / or when the shape of OAR 302 is particularly irregular.

[0052] Figure 3a Described with Figure 3b The features described correspond to the features, thus avoiding redundant interpretations of these features. Figure 3a In, relative to Figure 3bPTV 204, OAR 302, and buffer 304 have moved a distance d to the left. This is likely due to the subject moving a distance d to the left. While in this example, the subject's movement causes a corresponding movement of PTV 204, OAR 302, and buffer 304, in other examples, one or more of these features may move by different amounts in different directions. This could be caused, for example, by the movement of an internal portion of the subject relative to the subject's outer surface. The movement of PTV 204, OAR 302, and the subject as a whole may be directly or indirectly related to each other. Buffer 304, defined as the shell surrounding PTV 204, may not move relative to PTV 204 in this way. However, the techniques described herein may result in variations in the shape and size of buffer 304.

[0053] Although Figure 3b An example in which PTV 204, OAR 302, and buffer 304 have been shifted to the left by a distance d for ease of understanding is described, but it will be understood that other shifts are considered within the scope of this disclosure. In some examples, one or more of PTV 204, OAR 302, and buffer 304 may undergo periodic motion, for example due to the respiratory or cardiac cycles of the subject. In some examples, the position of one or more of PTV 204, OAR 302, and buffer 304, taken as a time-averaged position within one of these cycles, can be used to determine relative distances and buffers.

[0054] exist Figure 3a In the middle, the treatment area of ​​300 was not relative to Figure 3a Mobile. In other words, the radiotherapy device 100 can be moved. Figure 3b The same radiation applied to Figure 3b The same position in the same location. Since PTV 204, OAR 302, and buffer 304 have moved, while treatment area 300 has not, PTV 204, OAR 302, and buffer 304 have moved relative to treatment area 300. (As from...) Figure 3b It can be seen that the treatment area 300 is at least partially located outside the buffer zone 304. Specifically, in Figure 3b In the middle, a subset 306 of the treatment area 300 (shown as being filled with diagonals) is located outside the buffer zone 304.

[0055] According to the invention, the controller can determine that the treatment area 300 is at least partially located outside the buffer zone 304, that is, determine the existence of a subset 306 of the treatment area 304, such as Figure 3bAs shown. In particular, image data can provide information about the position and / or movement of anatomical structures within the subject and / or the subject. For example, based on known anatomical structures of the PTV 204 and surrounding tissues, it can be identified from the image data when the PTV 204 moves, by what distance, and in what direction. Since the buffer zone 304, defined as the shell surrounding the PTV 204, does not move relative to the PTV 204, the position and / or movement of the buffer zone can be determined from the movement of the PTV 204 (i.e., from the image data). Therefore, since the treatment area 300 has not moved, and since the position of the buffer zone 304 can be determined from the image data, it can be determined whether the treatment area 300 is at least partially located outside the buffer zone 304. In other examples, the treatment area 300 may, for example, move during treatment. The controller may have information about this movement, or may be communicatively coupled to a component that sends this information to the controller. Thus, when applying the currently disclosed techniques, the controller can appropriately update the position of the treatment area 300 in a time-related manner.

[0056] In response to determining that the treatment area 300 is at least partially located outside the buffer zone 304, the controller may generate control signals for adjusting the radiotherapy. The control signals may include one or more control signals sent to one or more components of the radiotherapy apparatus. Where the control signals are described as being sent to multiple components, the entire control signal may be sent to each of the multiple components, or a separate portion of the control signal may be sent to each component.

[0057] As described in more detail below, the controller can be configured to send control signals to the treatment control device. The treatment control device can be communicatively coupled to the controller. The treatment control device can be configured to receive and implement the control signals, for example, by acting on computer-executable instructions included in the control signals. The treatment control device can be configured to control or adjust radiotherapy based on the control signals. The treatment control device may include one or more of a radiation source, a beam tracking or beamforming component (e.g., collimator 108 or a multi-leaf collimator), a radiation source positioning system, and a patient positioning surface.

[0058] A control signal can be configured to adjust the output of a radiation source. The control signal can be configured to gate and / or reduce the dose rate of the radiation. In these examples, the control signal can be sent to at least the radiation source, and the control signal can gate and / or reduce the dose rate of the radiation. Figure 3b As shown, a subset 306 of the treatment area 300 overlaps with the OAR 302. Therefore, this control signal can prevent damage to the OAR 302 by shutting off the radiotherapy beam or reducing the dose rate of the radiotherapy beam.

[0059] Alternatively or additionally, a control signal can be generated and sent to a beam tracking or beamforming component, such as a collimator 108 (e.g., a multi-leaf collimator). This control signal can be configured to adjust the position of the treatment area 300, for example, to reposition it within the buffer zone 304. The control signal can be configured to cause the collimator 108 to adjust the shape of the radiotherapy beam. For example, the collimator 108 can be a multi-leaf collimator, and the control signal can be configured to adjust the position and / or orientation of one or more leaves of the multi-leaf collimator. For example, these techniques can enable the tracking of the radiotherapy beam to avoid irradiation outside the buffer zone 304. In some examples, the position and / or orientation of one or more leaves of the multi-leaf collimator can be adjusted such that the radiotherapy beam is blocked in a subset 306 of the treatment area 300, resulting in the subset 306 of the treatment area not being irradiated. Thus, irradiation outside the buffer zone 304 and inside the OAR 302 can be avoided.

[0060] Alternatively or additionally, control signals may be sent to the radiation source positioning system and may be configured to cause the radiation source positioning system to adjust the position and / or orientation of the radiation source. The radiation source positioning system may be part of bench 116, or the radiation source may be coupled to bench 116. The radiation source positioning system may include a radiation source positioning system controller configured to receive control signals and implement the control signals by moving the radiation source positioning system and / or the radiation source.

[0061] Alternatively or additionally, control signals can be sent to the patient positioning surface (also referred to herein as the patient support surface) to adjust the position and / or orientation of the patient positioning surface. This allows for adjustment of the target area's position relative to the radiation source. The patient positioning surface can move in three translational (x, y, z) and three rotational (roll, pitch, yaw) directions, i.e., its movement can have six degrees of freedom. Control signals can be configured to cause or adjust movement of the patient positioning surface in one, more, or all of these directions. The patient positioning surface may include a patient positioning surface controller configured to receive control signals and implement the control signals by moving the patient positioning surface.

[0062] Although Figure 3a The description of treatment area 300 is not yet relative to Figure 3a The example has been moved for ease of understanding, but it will be understood that in other examples, treatment area 300 can be... Figure 3b The first time point described in the text and Figure 3aThe movement occurs between the second time points described in the text. For example, PTV 204 can change over time during treatment and can be tracked across the subject's area to accommodate this. In these examples, the updated position of OAR 302 and / or the updated position of PTV 204 can be used to determine the relative distance between OAR 302 and PTV 204, and the buffer 304 based thereon, which may be based on image data from one or more imaging systems. In some examples, the radiotherapy apparatus can be configured such that the treatment area 300 moves within PTV 204. In such examples, the controller can still be configured to generate control signals to adjust the radiotherapy when the treatment area 300 is at least partially outside the buffer 304 at a particular time point.

[0063] The controller can be configured to receive image data from one or more imaging systems, determine relative distances, determine buffers, generate control signals, and / or transmit control signals during radiotherapy. One or more of these steps can be performed multiple times or consecutively during radiotherapy. The controller can also be configured to receive image data from one or more imaging systems, determine relative distances, determine buffers, generate control signals, and / or transmit control signals in real time during radiotherapy. Furthermore, the controller can be configured to dynamically receive image data from one or more imaging systems, determine relative distances, determine buffers, generate control signals, and / or transmit control signals during radiotherapy. Performing one or more of these steps in this dynamic / real-time manner during radiotherapy can be based on data from the MR imaging system. By implementing this dynamic change in the buffer during radiotherapy, more appropriate / accurate safety margins can be achieved to reduce radiotherapy interruptions and improve radiotherapy efficiency.

[0064] In some examples, it can be determined whether the subject or a portion of the subject has moved, and in response to determining that the subject or a portion of the subject has moved, one or more of the following can be performed: receiving image data from one or more imaging systems, determining a relative distance, determining a buffer, generating a control signal, and / or sending a control signal. In some examples, if it is determined at a subsequent time point that the subject or a portion of the subject has moved back to a previous position associated with a previous time point, the relative distance associated with the previous time point can be used as the relative distance for the subsequent time point and / or the buffer associated with the previous time point can be used as the buffer for the subsequent time point. Determining whether the subject or a portion of the subject has moved can be based on image data. Alternatively or additionally, the determination of whether the subject or a portion of the subject has moved can be based on one or more other sensors in the room where radiation therapy is being performed, such as a chest strap or camera.

[0065] In some examples, if it is determined that the subject or a portion of the subject has not moved relative to a previous time point, one or more of the following may not be performed: receiving image data from one or more imaging systems, determining relative distance, determining a buffer, generating control signals, and / or sending control signals, at least until a subsequent time point. In other words, in response to determining that the subject or a portion of the subject has not moved relative to a previous time point, the buffer from the previous time point may be retained / held for use.

[0066] In some examples, determining the buffer zone may include adjusting a previous buffer zone (e.g., a portion of a previous buffer zone). For example, the first side of the buffer zone may be adjusted based on the fact that the relative distance to the organ at risk on the first side has changed (e.g., has changed dynamically during treatment). The second side of the buffer zone may remain unchanged; that is, the portion of the previous buffer zone corresponding to the second side may be used for the second side of the adjusted buffer zone. This may be based on the fact that the anatomical structures near the second side remain unchanged relative to the point in time when the previous buffer zone was determined. Unchanged anatomical structures may indicate that the organ at risk on the second side is at the same distance from the target area on the second side, or at the same distance within a predetermined threshold, or that there is no organ at risk on the second side.

[0067] These steps enable improved use of previously determined distances and zones, and allow processing steps to be implemented only when necessary or justified based on the progress of radiotherapy. Therefore, these steps can improve the efficiency of available computational resources and increase the speed at which control signals for adjusting radiotherapy are generated.

[0068] In some examples, the target area may move according to a first vector, while the organ at risk remains stationary or moves according to a second vector. In other examples, the organ at risk may move according to the first vector, while the target area remains stationary or moves according to the second vector. This could be due, for example, to the effects of gravity, the subject's anatomy, the nature of the movement, and / or one or more of the subject's physiological cycles (e.g., breathing or cardiac activity). The target area and / or organ at risk and / or buffer zone may move with the subject, while the treatment area may be controlled to move relative to the frame of the room where radiotherapy is being performed.

[0069] According to the invention, the controller can determine the relative distance between the PTV 204 and the OAR 302 from image data, and the controller can determine, based on the image data, whether the treatment area 304 is at least partially located outside the buffer zone 300. The image data can be generated by one or more imaging systems. In some examples, the relative distance can be determined from a first time point (e.g., at...). Figure 3b The treatment area 300 can be determined based on image data acquired at the time point described in the text, and can be based on a second (later) time point (e.g., at...). Figure 3bThe image data acquired at the time point described in [the document] was determined to be at least partially located outside buffer 304. For ease of understanding, Figure 3b The first width w1 and the second width w2 are not described. However, it will be understood that since PTV 204, OAR302 and buffer 304 have respectively... Figure 3b The leftward movement distance d in the figure, therefore the corresponding relative distance between PTV 204 and OAR 302, the corresponding first width w1 and the corresponding second width w2 are respectively applicable to Figure 3a As it applies to Figure 3b The same. Therefore, the relative distance between PTV204 and OAR 302 can alternatively be determined from the same image data, based on which the treatment area 300 is determined to be at least partially located outside the buffer zone 304, i.e., in Figure 3b The second time point described in the text. In other words, due to Figure 3a The relative distance between PTV 204 and OAR 302 and Figure 3a The relative distances in the buffers are the same, so the same buffers (with the same first width w1 and second width w2) can be derived from this relative distance.

[0070] Image data from PTV 204 and / or OAR 302 can be time-related and can be generated continuously, intermittently, at predetermined time points and / or at the prompting of a clinician. This generation can occur during radiotherapy. In some examples, Figure 3a The first time point described can be during radiation therapy. In other examples, Figure 1The first time point described can be before the start of radiotherapy, for example, when the subject is in the treatment position. In some examples, the steps of determining the relative distance and the buffer zone can be performed based on image data generated by a first imaging system (e.g., a dedicated CT (computed tomography) scanner, a CBCT (cone-beam computed tomography) scanner, a field imaging system such as an electron field imaging device (EPID), a PET (positron emission tomography) scanner, or an ultrasound imaging system). In some examples, the step of generating a control signal in response to determining that the treatment area 300 is at least partially located outside the buffer zone 304 can be performed based on image data generated by a second imaging system (e.g., an MR imaging system). This image data can be generated during radiotherapy. The pre-treatment determination of the relative distance and buffer zone can be used to determine the initial treatment plan. In some examples, the relative distance and buffer zone can be re-determined during radiotherapy to dynamically update the treatment plan, for example, based on image data from the MR imaging system. In the context of image data generated by one or more imaging systems, all image data may be generated by a first imaging system, all image data may be generated by a second (or third, fourth, etc.) imaging system, or different portions of the image data may be generated by different imaging systems within one or more imaging systems.

[0071] The controller can use image data to continuously, intermittently, at predetermined time points and / or upon prompting from the clinician to determine or update relative distances and / or buffer zones 304. The controller can also use image data to continuously, intermittently, at predetermined time points and / or upon prompting from the clinician to determine whether the treatment zone 300 is at least partially outside the buffer zone, generating control signals and / or sending control signals to one or more components of the radiotherapy equipment. Therefore, these quantities and determinations can be dynamically recalculated and determined during radiotherapy, which can improve the accuracy and safety of radiotherapy. This allows for consideration of movement of different zones and physical characteristics of the subject during radiotherapy.

[0072] One or more of PTV 204, treatment area 300, OAR 302, buffer zone 304, and a subset 306 of treatment area 300 can be a two-dimensional area (i.e., area) or a three-dimensional area (i.e., volume). In other words, these features can be considered, stored, calculated, and / or determined by the controller in two or three dimensions, depending on the specific application, requirements, available sensors, available data, and available processing capabilities.

[0073] It will be understood that gating the therapeutic beam allows for the selective application of radiation during some time periods while refraining from applying radiation during other time periods. The radiation source may include particle sources, such as electron source 106, and radio frequency (RF) field sources 102 (e.g., ...). Figure 4(As shown). An electron source can provide a source of electrons, which generates the radiation dose to be delivered to the subject, for example, by impacting a target. An RF field source can electromagnetically accelerate electrons to a desired velocity suitable for delivering the radiation dose. The radiation source can be selected by selectively controlling the electron source to be on (activated) or off (deactivated). Alternatively or additionally, the radiation source 100 can be selected by selectively controlling the RF field source to be on (activated) or off (deactivated). In this way, the radiation dose applied by the radiation source can be controlled according to desired parameters (e.g., based on control signals according to the invention).

[0074] The radiation source may include a radiation source controller adapted to control the radiation source, for example, by gating the radiation source, stopping the gating of the radiation source, and / or adjusting the dose rate of the radiation source. The controller may send control signals to the radiation source controller. The control signals may include instructions for immediately, at a defined later time, after a defined interval, or some combination thereof, to perform such gating or stopping such gating or adjusting the dose rate. Therefore, the control signals may include instructions for time-varying or time-dependent gating of the beam by the radiation source and / or for adjusting the dose rate by the radiation source.

[0075] Figure 5 A method 400 for controlling a radiotherapy apparatus according to the present invention is described. This method can be performed using a radiotherapy apparatus 100 as currently disclosed. The method can be a computer-implemented method.

[0076] In step 402, radiation may be applied to the treatment area 300 of the subject. The radiation may be applied by a radiation source. The radiation may be applied according to the treatment plan.

[0077] In step 404, image data may be generated for the subject. The image data may be generated by one or more imaging systems, including magnetic resonance (MR) imaging systems. The image data may be two-dimensional or three-dimensional. The image data may be image data of the entire subject, or it may be image data of a subset of the subject including the treatment area 300 and / or the target area / PTV 204. During radiotherapy, i.e., while radiation is being applied to the subject, the image data may be generated repeatedly or continuously. Alternatively or additionally, the image data may be generated at a series of predetermined time points and / or at the prompting of a clinician. In some examples, at least a portion of the image data may be generated before treatment begins.

[0078] In step 406, the relative distance between the target area / PTV 204 and the organ at risk 302 can be determined based on image data. This determination can be performed by a controller communicatively coupled to the radiation source and one or more imaging systems. One or more imaging systems can transmit image data to the controller. This transmission can be repeated or continuous during radiotherapy, i.e., while radiation is being applied to the subject. Alternatively or additionally, transmission can be performed at a series of predetermined time points and / or at the prompting of a clinician. The relative distance can be a vector between the target area 204 and the organ at risk 302. This vector can be defined in two or three dimensions. The relative distance can be defined as the minimum distance between the surface of the target area 204 and the surface of the organ at risk 302. The surface of the target area 204 can be the isodose surface of the target area. Alternatively, the relative distance can be determined as the distance between the centroid of the target area 204 and the centroid of the organ at risk 302.

[0079] In step 408, a buffer zone 304 may be defined around the target region 204, at least in part, based on relative distance. This determination may be made by a controller. The buffer zone may be anisotropic. The buffer zone may extend beyond the target region by different distances in different directions. For a first direction from the target region 204 to the organ at risk 302 and a second direction different from the first direction, the buffer zone may extend a smaller distance (i.e., thinner) in the first direction than in the second direction.

[0080] In step 410, it can be determined whether the treatment area 300 is at least partially located outside the buffer zone 304. In other words, it can be determined whether a non-zero subset 306 of the treatment area 300 is located outside the buffer zone 304. This determination can be made by a controller. This determination can be based at least in part on the subject's image data. The image data can be the same image data mentioned in steps 404 and 406 above. Alternatively, the image data can be image data acquired at a later time point. One or more imaging systems can include a magnetic resonance imaging (MRI) system. The image data can be two-dimensional or three-dimensional. The image data can be image data of the entire subject, or it can be image data of a subset of the subject including the treatment area 300 and / or the target area 204. During radiotherapy, i.e., while radiation is being applied to the subject, the image data can be generated repeatedly or continuously. Alternatively or additionally, the image data can be generated at a series of predetermined time points and / or at the prompting of a clinician. In some implementations, the determination can include determining whether the treatment area 300 extends beyond the buffer zone 304 by at least a threshold amount. The threshold amount can be the absolute volume or percentage of the treatment area 300 or the target area 204.

[0081] In response to determining that the treatment area 300 is not at least partially outside the buffer 304, the method may return to step 402. Steps 402 through 410 may be performed sequentially or intermittently. In response to determining that the treatment area 300 is at least partially outside the buffer 304, the method may continue to step 412.

[0082] In step 412, a control signal for adjusting the radiotherapy may be generated. The control signal may be generated by a controller. The control signal may be configured to adjust the output of the radiation source. The control signal may be configured to gate the radiation source. Alternatively or additionally, the control signal may be configured to adjust (e.g., reduce) the dose rate of the radiation applied by the radiation source. The dose rate may be reduced based on the size of a subset 306 of the treatment area 300 located outside the buffer 304. In particular, the control signal may be configured to reduce the dose rate by a larger amount when a larger subset 306 of the treatment area 300 is located outside the buffer 304, and by a smaller amount when a smaller subset 306 of the treatment area 300 is located outside the buffer 304. Alternatively or additionally, the control signal may be configured to cause the radiation source positioning system to adjust the position and / or orientation of the radiation source. Alternatively or additionally, the control signal may be configured to cause the collimator 108 to adjust the shape of the radiotherapy beam. For example, the collimator 108 may be a multi-leaf collimator, and the control signal may be configured to adjust the position and / or orientation of one or more leaves of the multi-leaf collimator. Alternatively or additionally, the control signal may be configured to adjust the position and / or orientation of the patient positioning surface. This allows for adjustment of the target area's position relative to the radiation source.

[0083] In some examples, if the current dose rate is above a predetermined threshold and / or if the treatment area 300 is at least partially outside the buffer zone 304 for at least a predetermined time period, the controller may generate a control signal only for adjusting the output of the radiation source. This accommodates the fact that the organ at risk 302 may be able to withstand irradiation at a small or moderate dose rate for a small or moderate time period. This avoids unnecessary cessation of radiotherapy, thereby improving the efficiency of radiotherapy. The controller may determine the dose applied to the organ at risk or a portion thereof based on image data and the product of the dose rate and the amount of time the treatment area 300 is at least partially outside the buffer zone 304. In other words, the controller may be configured to generate and / or send a control signal further based on determining that the current dose rate is above a predetermined threshold and / or further based on determining that the treatment area 300 has been at least partially outside the buffer zone 304 for at least a predetermined time period. In response to determining that the treatment area 300 is at least partially outside the buffer zone 304, the controller may introduce a delay before generating or sending a control signal and may generate or send a control signal only if the dose rate is above a predetermined threshold and / or the treatment area 300 has been at least partially outside the buffer zone 304 for at least a predetermined time period.

[0084] Control signals can be sent to one or more components of the radiotherapy apparatus, such as the radiation source, radiation source positioning system, collimator 108 or multi-leaf collimator, and / or patient positioning surface. The control signals can be sent by a controller. The control signals can gate radiation from the radiation source, for example, by turning off the electron source or by turning off the RF field used to accelerate the electrons. Alternatively or additionally, the control signals can control the radiation source to reduce the dose rate applied by the radiation source, for example, by reducing the electron source or by reducing the RF field. Alternatively or additionally, the control signals can cause the radiation source positioning system to adjust the position and / or orientation of the radiation source. Alternatively or additionally, the control signals can cause the collimator to adjust the shape of the radiotherapy beam emitted by the radiation source (i.e., adjust the shape of the radiotherapy beam after it has been emitted by the radiation source). Alternatively or additionally, the control signals can cause adjustment of the position and / or orientation of the patient positioning surface.

[0085] One or more imaging systems may continue to generate image data after the transmission and / or implementation of control signals. The controller may use this image data to determine whether the treatment area 300 remains at least partially outside the buffer zone 304. If the treatment area 300 is no longer at least partially outside the buffer zone 304 at a later time point, the controller may generate additional control signals and send these additional control signals to the radiation source. These additional control signals may be configured to cause the radiation source to apply radiation, increase the dose rate of the applied radiation, cause the radiation source positioning system to adjust the position and / or orientation of the radiation source, and cause the collimator 108 to adjust the shape of the radiotherapy beam and / or adjust the position and / or orientation of the patient positioning surface.

[0086] Figure 6 A method 500 for generating control signals for a radiotherapy apparatus according to the present invention is described. This method can be performed using a controller of a radiotherapy apparatus 100 as currently disclosed. This method can be a computer-implemented method. Where the steps of method 500 correspond to or are similar to corresponding steps of method 400, it will be understood that corresponding features and / or interpretations are applicable.

[0087] In step 502, image data may be received for the subject. The image data may be generated and received from one or more imaging systems. One or more imaging systems may include a magnetic resonance (MR) imaging system. The image data may be two-dimensional or three-dimensional. The image data may be image data of the entire subject, or it may be image data of a subset of the subject including treatment area 300 and / or target area 204. During radiotherapy, i.e., while radiation is being applied to the subject, image data may be generated repeatedly or continuously. Alternatively or additionally, image data may be generated at a series of predetermined time points and / or at the prompting of a clinician. In some examples, at least a portion of the image data may be generated before treatment begins.

[0088] In step 504, the relative distance between the target region 204 and the organ at risk 302 can be determined based on the image data. The relative distance can be a vector between the target region 204 and the organ at risk 302. This vector can be defined in two or three dimensions. The relative distance can be defined as the minimum distance between the surface of the target region and the surface of the organ at risk 302. The surface of the target region 204 can be an isodose surface of the target region 204. Alternatively, the relative distance can be determined as the distance between the centroid of the target region 204 and the centroid of the organ at risk 302.

[0089] In step 506, a buffer zone 304 may be defined around the target region 204, at least in part, based on relative distance. This determination may be made by a controller. The buffer zone 304 may be anisotropic. The buffer zone 304 may extend beyond the target region 204 by different distances in different directions. For a first direction from the target region 204 to the organ at risk 302 and a second direction different from the first direction, the buffer zone 304 may extend a smaller distance (i.e., thinner) in the first direction than in the second direction.

[0090] In step 508, it can be determined whether the treatment area 300 of the subject is at least partially located outside the buffer zone 304. In other words, it can be determined whether a non-zero subset 306 of the treatment area 300 is at least partially located outside the buffer zone 304. This determination can be based at least in part on the subject's image data. The image data can be the same image data mentioned in steps 502 and 504 above. Alternatively, the image data can be image data acquired at a later time point. One or more imaging systems can include a magnetic resonance (MR) imaging system. The image data can be two-dimensional or three-dimensional. The image data can be image data of the entire subject, or it can be image data of a subset of the subject including the treatment area 300 and / or the target area 204. During radiotherapy, i.e., while radiation is being applied to the subject, the image data can be generated repeatedly or continuously. Alternatively or additionally, the image data can be generated at a series of predetermined time points and / or at the prompting of a clinician. In some implementations, it can be determined whether the treatment area 300 extends beyond the buffer zone 304 by at least a threshold amount. The threshold amount can be the absolute volume or percentage of the treatment area 300 or the target area 204.

[0091] In response to determining that the treatment area 300 is not at least partially outside the buffer 304, the method may return to step 502. Steps 502 through 508 may be performed consecutively or intermittently. In response to determining that the treatment area 300 is at least partially outside the buffer 304, the method may continue to step 510.

[0092] In step 510, a control signal for adjusting radiotherapy may be generated. The control signal may be configured to adjust the output of the radiation source. The control signal may be configured to gate the radiation source. Alternatively or additionally, the control signal may be configured to adjust (e.g., reduce) the dose rate of radiation applied by the radiation source. Alternatively or additionally, the control signal may be configured to cause the radiation source positioning system to adjust the position and / or orientation of the radiation source. Alternatively or additionally, the control signal may be configured to cause the collimator 108 to adjust the shape of the radiotherapy beam emitted by the radiation source (i.e., adjust the shape of the radiotherapy beam after it has been emitted by the radiation source). Alternatively or additionally, the control signal may be configured to adjust the position and / or orientation of the patient positioning surface.

[0093] The controller can continue receiving image data after the control signal is sent. The controller can use this image data to determine whether the treatment area 300 continues to be at least partially outside the buffer zone. If the treatment area 300 is no longer at least partially outside the buffer zone 304 at a later time point, the controller can generate an additional control signal and send this additional control signal to the radiation source. This additional control signal can be configured to cause the radiation source to apply radiation, increase the dose rate of the applied radiation, cause the radiation source positioning system to adjust the position and / or orientation of the radiation source, and cause the collimator 108 to adjust the shape of the radiotherapy beam and / or adjust the position and / or orientation of the patient positioning surface.

[0094] The apparatus disclosed herein can be configured to perform any of the method steps disclosed herein, and may include computer-executable instructions that, when executed by a processor, cause the processor to perform any of the method steps disclosed herein. Any step that the apparatus is configured to perform can be considered a method step of the present invention, and can be embodied in computer-executable instructions for execution by a processor.

[0095] Although the methods disclosed herein are presented in a specific order, this should not be construed as limiting the methods to the presented order. One or more method steps may be omitted or rearranged. The steps may be performed in a different order. The steps may be performed simultaneously or substantially simultaneously. In this document, references to substantially simultaneous events may refer to events that at least partially overlap in time with the intrinsic time of the measurement uncertainty and / or events that occur simultaneously.

[0096] This article provides a computer-implemented method comprising: receiving image data from one or more imaging systems for a subject; determining a relative distance between a target area and an organ at risk based on the image data; determining a buffer zone around the target area based at least partially on the relative distance; and generating a control signal for adjusting radiotherapy in response to the subject's treatment area being at least partially outside the buffer zone.

[0097] A computer-implemented method may include: sending a control signal to a radiation source, wherein the control signal is configured to adjust the output of the radiation source. The control signal may be configured to gate the application of radiation by the radiation source. The control signal may be configured to reduce the dose rate of radiation by the radiation source. The control signal may be configured to reduce the dose rate of radiation by the radiation source based on the size of a subset of the treatment area located outside the buffer zone.

[0098] The computer-implemented method may include sending control signals to a radiation source positioning system, wherein the control signals are configured to cause the radiation source positioning system to adjust the position and / or orientation of the radiation source.

[0099] A computer-implemented method may include sending control signals to a collimator, wherein the control signals are configured to cause the collimator to adjust the shape of a radiotherapy beam emitted by a radiation source. The collimator may be a multi-leaf collimator, wherein configuring the control signals to cause the collimator to adjust the shape of the radiotherapy beam includes: the control signals being configured to adjust the position and / or orientation of one or more leaves of the multi-leaf collimator.

[0100] The computer-implemented method may include sending control signals to a patient positioning surface, wherein the control signals are configured to adjust the position and / or orientation of the patient positioning surface.

[0101] The buffer zone can be anisotropic. It can extend beyond the target area by different distances in different directions. The first width of the buffer zone in the first direction where the organ at risk is located can be less than the second width of the buffer zone in the second direction where no organ at risk is located.

[0102] Computer-implemented methods may include: determining the shape of the target region and / or the shape of the organ at risk based on image data; and determining a buffer zone around the target region based at least in part on the shape of the target region and / or the shape of the organ at risk.

[0103] The computer-implemented method may include generating and / or sending control signals based on determining that the current dose rate is higher than a predetermined threshold and / or based on determining that the treatment area is at least partially outside the buffer for at least a predetermined time period.

[0104] The image data may be three-dimensional image data, wherein the computer-implemented method includes: determining a relative distance in three dimensions, determining a buffer zone in three dimensions, and determining whether the treatment area is at least partially located outside the buffer zone in three dimensions. One or more imaging systems may include a magnetic resonance imaging system.

[0105] Computer-implemented methods may include: receiving image data from one or more imaging systems multiple times or continuously during radiotherapy, determining relative distances, determining buffers, generating control signals, and / or sending control signals.

[0106] Computer-implemented methods may include: determining the corresponding relative distance between the target area and each of a plurality of organs at risk based on image data; and determining a buffer zone around the target area based at least in part on the relative distance.

[0107] ​A block diagram illustrating one implementation of a computing device 600 is provided, within which a set of instructions can be executed to cause the computing device to perform any or more of the methods discussed herein. In alternative implementations, the computing device may be connected (e.g., networked) to other machines in a local area network (LAN), intranet, extranet, or the Internet. The computing device may operate as a server or client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The computing device may be a personal computer (PC), tablet computer, set-top box (STB), personal digital assistant (PDA), cellular phone, network appliance, server, network router, switch, or bridge, or any machine capable of executing a set of instructions (sequentially or otherwise) specifying the action to be taken by the machine. Further, although only a single computing device is illustrated, the term "computing device" should also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or more) of instructions to perform any or more of the methods discussed herein.

[0108] Example computing device 600 includes processing device 602, main memory 604 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), static memory 606 (e.g., flash memory, static random access memory (SRAM), etc.), and auxiliary memory (e.g., data storage device 618), which communicate with each other via bus 630.

[0109] Processing device 602 represents one or more general-purpose processors, such as microprocessors, central processing units, etc. More specifically, processing device 602 may be a Complex Instruction Set Computing (CISC) microprocessor, a Reduced Instruction Set Computing (RISC) microprocessor, a Very Long Instruction Word (VLIW) microprocessor, a processor implementing other instruction sets, or a processor implementing a combination of instruction sets. Processing device 602 may also be one or more special-purpose processing devices, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), network processors, etc. Processing device 602 is configured to execute processing logic (instructions 622) for performing the operations and steps discussed herein.

[0110] The computing device 600 may also include a network interface device 608. The computing device 600 may also include a video display unit 610 (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)), an alphanumeric input device 612 (e.g., a keyboard or a touch screen), a cursor control device 614 (e.g., a mouse or a touch screen), and an audio device 616 (e.g., a speaker).

[0111] Data storage device 618 may include one or more machine-readable storage media (or more specifically, one or more non-transitory computer-readable storage media) 628, on which one or more sets of instructions 622 specifically implementing any or more of the methods or functions described herein are stored. The instructions 622 may also reside wholly or at least partially within main memory 604 and / or processing device 602 during execution by computer system 600, which also constitute computer-readable storage media.

[0112] The various methods described above can be implemented by a computer program. A computer program may include computer code arranged to instruct a computer to perform the functions of one or more of the methods described above. The computer program and / or code for performing these methods may be provided to a device, such as a computer, on one or more computer-readable media, or more generally, on a computer program product. The computer-readable media may be transient or non-transient. The one or more computer-readable media may be, for example, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, or a propagation medium for data transmission (e.g., for downloading code via the Internet). Alternatively, the one or more computer-readable media may take the form of one or more physical computer-readable media, such as semiconductor or solid-state memory, magnetic tape, removable computer disk, random access memory (RAM), read-only memory (ROM), hard disk, and optical disk (e.g., CD-ROM, CD-R / W, or DVD).

[0113] In implementation, the modules, components, and other features described herein may be implemented as discrete components or integrated into the functionality of hardware components such as ASICs, FPGAs, DSPs, or similar devices.

[0114] A "hardware component" is a tangible (e.g., non-transient) physical component (such as a group or one or more processors) capable of performing certain operations and which can be configured or arranged in some physical manner. A hardware component may include dedicated circuitry or logic permanently configured to perform certain operations. A hardware component may be or include dedicated processors, such as field-programmable gate arrays (FPGAs) or ASICs. A hardware component may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations.

[0115] Therefore, the phrase “hardware component” should be understood to encompass tangible entities that can be physically constructed, permanently configured (e.g., hardwired) or temporarily configured (e.g., programmed) to operate or perform certain operations described herein.

[0116] Furthermore, modules and components can be implemented as firmware or functional circuitry within a hardware device. Further, modules and components can be implemented as any combination of hardware devices and software components, or solely as software (e.g., code stored or otherwise embodied in a machine-readable medium or transmission medium).

[0117] Unless otherwise specifically stated, it should be understood from the following discussion that throughout the specification, the use of terms such as “receive,” “determine,” “compare,” “implement,” “maintain,” “identify,” “apply,” “send,” “generate,” etc., refers to the actions and processes of a computer system or similar electronic computing device that manipulates data represented as physical (electronic) quantities in the registers and memories of the computer system and transforms it into other data similarly represented as physical quantities in the computer system’s memory or registers or other such information storage, transmission, or display devices.

[0118] The methods described herein can be implemented on a computer-readable medium, which may be a non-transient computer-readable medium. The computer-readable medium may carry computer-readable instructions arranged to execute on a processor so as to cause the processor to perform any or all of the methods described herein.

[0119] As used herein, the term "computer-readable medium" refers to any medium that stores data and / or instructions for causing a processor to operate in a particular manner. Such storage media can include non-volatile media and / or volatile media. Non-volatile media can include, for example, optical discs or magnetic disks. Volatile media can include dynamic memory. Exemplary forms of storage media include floppy disks, floppy disks, hard disks, solid-state drives, magnetic tape or any other magnetic data storage media, CD-ROMs, any other optical data storage media, any physical media with a pattern of one or more holes, RAM, PROMs, EPROMs, flash EPROMs, NVRAMs, and any other memory chips or cartridges.

[0120] It should be understood that the above description is intended to be illustrative and not restrictive. Many other implementations will become apparent to those skilled in the art upon reading and understanding the above description. Although the invention has been described with reference to specific exemplary implementations, it will be appreciated that the invention is not limited to the described implementations but can be practiced with modifications and variations within the scope of the appended claims. Therefore, the specification and drawings should be considered illustrative and not restrictive. Consequently, the scope of the invention should be determined by reference to the appended claims and the full scope of their authorized equivalents.

Claims

1. A radiation therapy device, comprising: a radiation source configured to apply radiation to a treatment region coinciding with a subject in accordance with a treatment plan; one or more imaging systems configured to generate image data for the subject; and a controller communicatively coupled to the radiation source and the one or more imaging systems, the controller configured to: determine a relative distance between a target region of the subject and a critical organ of the subject based on the image data, wherein the treatment plan includes a prescribed dose for the target region; determine a buffer region around the target region based at least in part on the relative distance; and generate a control signal for adjusting radiation therapy in response to determining, based on the image data, that the treatment region is at least partially located outside the buffer region. the controller is configured to send the control signal to the radiation source, and the control signal is configured to adjust an output of the radiation source.

2. The radiotherapy device of claim 1, wherein, the control signal is configured to cause the radiation source to gate application of radiation.

3. The radiotherapy device of claim 2, wherein, the control signal is configured to cause the radiation source to reduce a dose rate of radiation.

4. The radiotherapy device of claim 2 or 3, wherein, the control signal is configured to cause the radiation source to reduce the dose rate of radiation based on a size of a subset of the treatment region that is located outside the buffer region.

5. The radiotherapy device of claim 4, wherein, the controller is configured to send the control signal to a radiation source positioning system, and the control signal is configured to cause the radiation source positioning system to adjust a position and / or orientation of the radiation source.

6. The radiotherapy device of claim 1, wherein, the controller is configured to send the control signal to a collimator, and the control signal is configured to cause the collimator to adjust a shape of a radiation therapy beam emitted by the radiation source.

7. The radiation treatment device of claim 1, wherein, the collimator is a multi-leaf collimator, and wherein the control signal being configured to cause the collimator to adjust the shape of the radiation therapy beam includes the control signal being configured to adjust a position and / or orientation of one or more leaves of the multi-leaf collimator.

8. The radiotherapy device of claim 7, wherein, the controller is configured to send the control signal to a patient positioning surface, and the control signal is configured to adjust a position and / or orientation of the patient positioning surface.

9. The radiation treatment device of claim 1, wherein, the buffer region is anisotropic.

10. The radiation treatment device of claim 1, wherein, the buffer region extends beyond the target region by different distances in different directions.

11. The radiotherapy device of claim 1, wherein, a first width of the buffer region in a first direction in which the critical organ is located is less than a second width of the buffer region in a second direction in which the critical organ is not located.

12. The radiotherapy device of claim 1, wherein, the controller is configured to:

13. The radiation treatment device of claim 1, wherein, determine a shape of the target region and / or a shape of the critical organ based on the image data; and determine the buffer region around the target region based at least in part on the shape of the target region and / or the shape of the critical organ. the controller is configured to generate and / or send the control signal further based on determining that a current dose rate is above a predetermined threshold and / or further based on determining that the treatment region has been at least partially located outside the buffer region for at least a predetermined period of time. the image data is three-dimensional image data, and wherein the controller is configured to determine a three-dimensional relative distance, determine a three-dimensional buffer region, and determine whether the treatment region is at least partially located outside the three-dimensional buffer region.

14. The radiotherapy device of claim 1, wherein, ​ 15. The radiotherapy device of claim 1, wherein, ​ 16. The radiotherapy device of claim 1, wherein, The one or more imaging systems comprise a magnetic resonance imaging system.

17. The radiotherapy device of claim 1, wherein, The controller is configured to receive image data from the one or more imaging systems, determine the relative distances, determine the buffer zone, generate the control signal, and / or send the control signal multiple or continuously during radiation therapy.

18. The radiotherapy device of claim 1, wherein, The controller is configured to: determine respective relative distances between the target volume and each of a plurality of organs at risk based on the image data; and determine the buffer zone around the target volume based at least in part on the relative distances.

19. A computer-readable medium comprising computer-executable instructions that, when executed by a processor, cause the processor to perform steps comprising: receiving image data for a subject from one or more imaging systems; determining a relative distance between a target volume of the subject and an organ at risk of the subject based on the image data, wherein a treatment plan includes a prescribed dose for the target volume; determining a buffer zone around the target volume based at least in part on the relative distance; and generating a control signal for adjusting radiation therapy in response to a treatment region coinciding with the subject being at least partially outside the buffer zone.

20. The computer readable medium of claim 19, wherein, The computer-executable instructions, when executed by the processor, cause the processor to further perform steps comprising sending the control signal to one or more of a radiation source, a radiation source positioning system, a collimator, a multi-leaf collimator, or a patient positioning surface.

21. The computer-readable medium of claim 19 or 20, wherein: the buffer zone is anisotropic; the buffer zone extends beyond the target volume by different distances in different directions; and / or a first width of the buffer zone in a first direction in which the organ at risk is located is less than a second width of the buffer zone in a second direction in which the organ at risk is not located.

22. The computer readable medium of claim 19, wherein, The computer-executable instructions, when executed by the processor, cause the processor to further perform steps comprising: determining a shape of the target volume and / or a shape of the organ at risk based on the image data; and determining the buffer zone around the target volume based at least in part on the shape of the target volume and / or the shape of the organ at risk.

23. The computer readable medium of claim 19, wherein, The computer-executable instructions, when executed by the processor, cause the processor to further perform steps comprising: generating and / or sending the control signal further based on determining that a current dose rate is above a predetermined threshold and / or further based on determining that the treatment region has been at least partially outside the buffer zone for at least a predetermined period of time.

24. The computer-readable medium of claim 19, wherein: the image data is three-dimensional image data, and the computer-executable instructions, when executed by the processor, cause the processor to further perform steps comprising determining a three-dimensional relative distance, determining a three-dimensional buffer zone, and determining whether the treatment region is at least partially outside the three-dimensional buffer zone; and the treatment region is at least partially outside the three-dimensional buffer zone. The computer executable instructions, when executed by the processor, cause the processor to further perform steps comprising receiving image data from the one or more imaging systems multiple times or continuously during radiation treatment, determining the relative distances, determining the buffer, generating the control signals, and / or sending the control signals; and / or determining respective relative distances between the target volume and each of a plurality of organs at risk based on the image data; and determining the buffer around the target volume based at least in part on the relative distances.

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